1. Field
The disclosure relates to a resistance heating element, and a heating member and a fusing device including the resistance heating element.
2. Description of the Related Art
A relative change of electric resistance according to change of temperature of a resistance heating element is defined as a temperature coefficient of electrical resistance. A resistance heating element is referred to as having a negative temperature coefficient (“NTC”) tendency when the resistance thereof decreases as temperature increases, and a resistance heating element is referred to as having a positive temperature coefficient (“PTC”) tendency when the resistance thereof increases as temperature increases. While most of materials exhibit PTC tendencies, nano-composite materials may exhibit NTC tendencies according to material properties of matrixes and combinations of fillers.
Resistance heating elements may be applied to various fields. For example, a resistance heating element may be applied to a fusing device of an electrophotographic image forming apparatus. An electrophotographic image forming apparatus forms a visible toner image on an image receptor by supplying a toner to an electrostatic latent image formed on the image receptor, transfers the toner image to a printing medium, and fuses the transferred toner image to the printing medium. A toner is typically manufactured by adding various functional additives, such as colorants, to a base resin. A fusing operation includes applications of heat and pressure to a toner. Substantial portion of energy consumed by an electrophotographic image forming apparatus is consumed during a fusing operation. A resistance heating element may be employed as a heating member for applying heat to a toner. At a fusing device of an image forming apparatus, if resistance of a resistance heating element changes significantly during the initial warm-up, applied power changes significantly during a short period of time such that overheating may occur.